Multicasting is a method for simultaneously delivering data over a network from a data source to a number of data receivers in a multicast group. Multicasting systems employ routing protocols to link the data sources to the appropriate data receivers in an efficient manner.
Multicasting networks are provided by multicast enabled nodes within or connected to an existing network. The nodes comprise multicast sources, multicast receivers and multicast routers. A multicast source is a source of the multicast data that is carried via the network to multicast receivers. The multicast routers are arranged to route the multicast packets across the network between the multicast sources and receivers.
A loop is a cyclical path which causes a packet to return to a node on the path from which node the packet has already been transmitted. For multicast traffic, route looping can pose issues. A looping multicast packet continuously generates copies as it loops, which in turn generates additional copies. These looping multicast packets begin to saturate the link which can quickly paralyze the network and significantly impact performance for routing other network traffic.